Electric translating device



Dec. 15, 1931. Y J. c. BENJAMIN 1,836,569

ELECTRIC TRANSLATING DEVICE Filed Dec. 21, 1927 4/NVENTORI JOH (J. BEA/JA MIN 4 z,' w g Arm/mm Patented Dec. 1931 UNITED STATES PATENT OFFICE JOHN C. mum, NEW YORK, N. Y., ASSIGNOR TO BELL TELEPHONE LABORA- TORIES, INCORPORATED, OE YORK, N. Y., A CORPORATION OF NEW YORK ELECTRIC TRANSLATING DEVICE Application filed December 21, 1927. Serial No. 241,714.

This invention relates to electric translating devices and more particularly to devices of the electric discharge type for changing mechanical vibrations into varying electric j current.

An object of the invention is to produce varying electric current by a directional change in an electronic stream without appreciable change in the space current thereof.

A particular arrangement, illustrative of the invention, comprises an evacuated vessel in which an electronic stream emitted from a hot cathode impinges equally upon a pair of plate electrodes which are located in a plane perpendicular to the axis of the stream. Each electrode of the pair of plate electrodes is connected respectively to a terminal of the primary winding of a transformer, the midpoint of which is connected through a source of potential to the cathode. By suitable means for shifting the direction of the stream in accordance with sound waves impinging upon a diaphragm the portion of the stream impinging upon each plate electrode is varied, thereby producing a varying current in the secondary winding of the transformer corresponding to the exciting sound waves.

The invention will now be described more in detail having reference to the accompanying drawings.

Fig. 1 is a diagrammatic View of the discharge type of translating device made in accordance with this invention showing the arrangement of the elements in the device and the speech actuated diaphragm for controlling the direction of the electronic stream.

Fig. 2 is a modified form of the invention in which the electronic stream is mechanically controlled in accordance with speech vibrations.

Referring to Fig. 1, the electric translating device comprises a cylindrical glass enclosing vessel 10 having an elongated narrow portion 11 coaxial therewith. A filament or cathode 12 is sealed in the closed end of the elongated portion 11 and an inwardly projecting stem 13 is sealed into the other end of the vessel and is provided to support a pair of plate electrodes 0r collector elements 14 and 15 in a plane perpendicular to the axis of the vessel. These plates are arranged with their inner edges close together but insulated from each other so that there is no electrical connection between them and are supported in the vessel at a considerable distance from the cathode 12. An apertured disc 16 and the plate electrodes 14 and 15.

The enclosim vessel may be highly evacuated, in a well-known manner, in order that a pureelectron discharge may pass between the main electrodes, or the vessel ma be filled with an easily ionized gas, suc as argon, to facilitate the passage of the gaseous discharge between the main electrodes. The cathode is connected to a battery 18 and an adjustable resistance 19, to heat the cathode whereby electrons are emitted. The plate electrode 14 is connected to one side of the primary winding of transformer 20 while the other plate electrode 15 is connected to the other side of the primary winding of trans former 20. A positive potential is applied to the plate electrodes by connecting the positive side of battery 21 to the mid-point of the primary winding of transformer 20 over conductor 22, and the negative side of battery 21 is connected to the cathode 12 over conductor 23. A positive potential is also applied to the auxiliary plate electrode 17 from battery 21, to draw the electrons from the cathode through the perforated disc 16. Since the main plate electrodes are at a higher positive potential than the auxiliary electrode 17, the electronic stream will be drawn toward these plate electrodes. The electronic stream is normally directed to equal portions of the plate electrodes 14 and 15 and causes current to flow equally in both halves of the primary winding of transformer 20 which results in no potential being 'generated in the secondary winding.

The device may be employed in the translation of mechanical energy into electrical energy by controlling the direction of the elec-' tronic stream to various portions of the main plate electrodes. As shown in Fig. 1, a diaphragm 24 associated with an electro-magnetic winding or coil 25, connected to a battery 26, is arranged on one side of the elongated portion 11 of the vessel. The winding 25 is preferably located intermediate the apertured focusing disc 16 and the auxiliary late electrode 17 and in a plane perpendicuar to the center of the plate electrode 14. A balancing coil or winding 27 energized by battery 28 and adjusted by a variable resistance 29 is positioned on the other side of the elongated portion 11 of the vessel diametrically opposite the winding 25 and the diaphragm 24:. The controlling winding 25 and the balancing winding 27 produce a magnetic field which maintainsthe electronic stream emitted from the cathode in its path along the axis of the vessel whereby the electrons im pinge on equal portions of the plate electrodes 14 and 15 and produce a constant flow of current in equal branches of the primary winding of transformer 20. \Vhen speech or other sound waves impinge on the diaphragm 24 the magnetic field controlling the electronic stream is altered due to the change position of the winding 25 and causes the electronic stream within the vessel to be deflected in its path from one plate electrode to the other. This deflection of the stream in the vicinity of the apcrtured disc 16 causes a large displacement of the stream at the surfaces of the plate electrodes 14 and 15. Consequently, a larger portion of the-beam is shifted to either surface of the plate electrodes,.thereby varying the current flow in the primary winding of transformer 20 and producing correspondingly potential variations at the output terminals of the second ary winding. FOIflIlStfiIlCG, if the electronic stream is deflected toward the collector element or plate electrode 15, the current flow.- ingin the upper half of the primary winding of transformer20 connected to the plate electrode 14.will be decreased, due to the small portion of the beam-impinging on this electrode. The current inthe lower half of the transformer 20 'will-be increased by a cone sponding amount; due to the greater portion of the beam impinging on the plate electrode 15. The variationsin current in the primary winding cause corresponding potentials to be generated in the secondary winding. The potential variations in the output circuit of the device bear a directflrelationto the 'me chanical variations impressed on the external I diaphragm adjacent the cathode, and maybe amplified or reproduced byconnecting an amplifier, receiver, recorder or measuring instrument (not shown) to the output terminals of the secondary winding of transformer 20. It will be seen from the above description that the changesfin output potentia are not accomplished by changes in s ace current between the electrodes since t e space current remains substantially con-.

by a rigid connecting member 32. The diaphragm is sealed into the wall of the vessel 33 which contains the cathode 34 at one end and the collector elements or plate electrodes 35 and 36 at the other end of the vessel. The cathode, focusing disc and plate electrodes are arranged in the vessel in a manner similar to that described in connection with Fig. 1. The cathode is heated by a battery 37 while a positive potential is applied to the plate electrodes 35 and 36 by a battery 38 connected to the cathode and the mid-point of the pr'imar winding of transformer 39. The ends oft e primary winding are connected to the plate electrodes 35 and 36 respectively, the same as described in Fig. 1.

In this arrangement the vibration of the diaphragm 31, due to the speech or other sound waves impinging thereon, causes the focusmg disc 30 to be vibrated accordingly. Since only the portion of the electronic stream which passes through the perforated disc 30 is directed to the plate electrodes 35 and 36 which in normal position allows the stream to impinge e ually upon both electrodes, it follows that ii the disc is vibrated by the diaphragm a portion of the beam is cut off from one plate electrode. The other plate electrode will therefore receive a greater portion of the cathode beam and thereby change the flow of current in the primary winding of transformer 39. The current variations in the transformer 39 will be similar to the current variations in transformer 20 described in connection with Fig. 1 and the mechanical energy imparted to the diaphragm 31 by speech waves will cause corresponding electrical variatlons 1n closing vessel, a cathode at one end of said vessel, a pair of collector elements at the other end of said vessel, said elements being in a plane at right angles to the axis of said A cathode, means to focus an electronic stream from said cathode toward said collector elements, and sound responsive means including a diaphragm for controlling said stream to shift said stream to variable portions of said collector elements.

2. A. translating device for converting mechanical vibrations into electrical impulses comprising an. evacuated enclosing Vessel having a cathode positioned in one end thereof, a pair of plenary plate elements positioned at the other end of said vessel, the adjacent edges of said elements being on either side of the axis of said cathode, an aperturcd disc located between said cathode and plate elements, said disc being relatively close to said cathode and parallel with said plate elements, and sound responsive means adjacent said cathode and disc for modulating the electron stream between said cathode and said plate elements.

3. A device for converting mechanical vibrations into electrical'impulses comprising an evacuated enclosing vessel having a cathode positioned in one end thereof, a pair of planary late elements positioned within and at the o er end of said vessel, the adjacent edges of said elements being on either side of the common axis of said cathode and vessel, an apertured disc located between said cathode and plate elements, said disc being relatively close to said cathode, an auxiliary cylindrical plate element located between said apertured disc and planary plate elements, and a. diaphragm exterior to said vessel and adjacent said cathode for modulating the electron stream between said cathode and said planary plate elements. a

4. An electronic microphone comprising an enclosing vessel containing a pair of collector plates, a cathode, and an apertured element coaxial with said cathode and a vibratile diaphragm adjacent said cathode and apertured element for acting upon the cathode ray beam.

5. An electronic microphone comprising an enclosing vessel, a cathode positioned at one end of said vessel, a pair of planary plate elements positioned at the other end of said vesel, and an apertured disc located adjacent said cathode and between said cathode and plate elements, said apertured disc normally directing said stream to equal portions of said plate elements, and means including a, diaphragm located external to said vessel adjacent said cathode and apertured disc, said diaphragm bein responsive to sound waves.

In witness w ereof, I hereunto subscribe my name this 19th day of December, A. D.

JOHN C. BENJAMIN. 

